Formal:
* Truant: This is the most formal and widely recognized term for someone who is absent from school without a valid excuse.
* School absentee: This is a more neutral term that avoids judgment and simply describes the act of being absent.
Informal:
* Skipper: This is a slang term for someone who skips school.
* Cut class: This refers to someone who skips a specific class, not the whole day.
* Play hooky: This is a more playful term for skipping school, often used for a single day or short period.
Other options:
* Non-attender: This term can be used for someone who is habitually absent from school, regardless of the reason.
* School dropout: This term is reserved for someone who has completely stopped attending school, usually without completing their education.
The best term to use will depend on the specific situation and the level of formality required.